POWER __builtin_add_overflow/__builtin_mul_overflow with u64

[Simon Richter]

Hi,

I'm looking at the generated code for these builtins on POWER:

        add 4,3,4
        subfc 3,3,4
        subfe 3,3,3
        std 4,0(5)
        rldicl 3,3,0,63
        blr

and

        mulld 10,3,4
        mulhdu 3,3,4
        addic 9,3,-1
        std 10,0(5)
        subfe 3,9,3
        blr





   Simon

The POWER architecture has variants of these instructions with builtin overflow checks (addo/mulldo), but these aren't listed in the .md files, and the builtins don't generate them either. Is this intentional (I've found a few comments that mulldo is microcoded on CellBE and should be avoided there)?

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